1. Field of the Invention
The present invention generally relates to a receiver system for ultra wideband (UWB). More particularly, the present invention relates to a UWB receiver system capable of completely removing interference by WLAN band signal.
2. Description of the Prior Art
UWB communications utilizes wide frequency band and thus enabled high-speed data transmission with very low power consumption. The UWB communications use frequency band of 3.1˜10.6 GHz, and HIPERLAN/2 or IEEE 802.11a, the WLAN communication service standards. Particularly a frequency band of 5.15˜5.825 GHz is used. Because power at WLAN band is higher than that of UWB communication system by more than 70 dB, the UWB communication system may suffer electromagnetic interference by WLAN signal. Accordingly, ways to remove WLAN frequency signals from the UWB communication signals have been conventionally studied and suggested. One of the conventional suggestions uses a band stop filter (BSF) at the end of the RF receiver system.
FIG. 1 is a block diagram of the structure of a RF receiver system using an UWB antenna. Referring to FIG. 1, a conventional receiver system includes a UWB antenna 1, a filter 2, and an amplifier 3.
The UWB antenna 1 receives signals of the frequency band of 3.1˜10.6 GHz.
The filter 2 operates to remove signals of 5.15˜5.825 GHz from the signals received at the UWB antenna 1. The filter 2 includes a BSF (band stop filter) which does not let the signals of a predetermined frequency band pass through, thereby filtering off the predetermined frequency band.
The amplifier 3 operates to amplify received signals and output the amplified signals at the rear end.
In the conventional receiver system, the UWB antenna 1 and the filter 2 are respectively implemented as independent circuits. Accordingly, the size of the receiver system is increased. Additionally, because the receiver system has a plurality of components significant power loss occurs. Further, the system has a complicated structure. Additionally, although the conventional filter 2 may remove a part of the WLAN signals, the power of 70 dB in the WLAN band cannot be completely controlled.
Accordingly, techniques for removing WLAN band power completely from the UWB communication, and thus removing interference by the WLAN signals, is required.